100. Same Tree

Given two binary trees, write a function to check if they are the same or not.

Two binary trees are considered the same if they are structurally identical and the nodes have the same value.

Example 1:

Input:     1         1
          / \       /          2   3     2   3

        [1,2,3],   [1,2,3]

Output: true

Example 2:

Input:     1         1
          /                    2             2

        [1,2],     [1,null,2]

Output: false

Example 3:

Input:     1         1
          / \       /          2   1     1   2

        [1,2,1],   [1,1,2]

Output: false

 判断两棵二叉树是否完全一样

C++（3ms）：

 1 /**
 2  * Definition for a binary tree node.
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     bool isSameTree(TreeNode* p, TreeNode* q) {
13         if (p == NULL || q == NULL)
14             return p == q ;
15         return p->val == q->val && isSameTree(p->left , q->left) && isSameTree(p->right , q->right) ;
16     }
17 };